Büchner flask

Preferably this is done through a trap (see below), which is designed to prevent the sucking back of water from the aspirator into the Büchner flask.

The purpose of applying a vacuum is to speed the filtration by providing a pressure differential across the filter medium that is greater than that produced by gravity alone.

The thick wall of the Büchner flask provides it the strength to withstand the pressure difference while holding a vacuum inside.

The Büchner funnel holds the sample isolated from the suction by a layer of filter paper.

The flask is named after the industrial chemist Ernst Büchner, who invented it, despite the mistaken belief held by many people that it's named after chemist and Nobel Laureate Eduard Buchner.